1. Field of the Invention
This invention relates to an automobile body structure, and more particularly to a monocoque type automobile body structure.
2. Description of the Prior Art
In order to increase the rigidity of an automobile body structure, it has been proposed, as disclosed in Japanese Unexamined Utility Model Publication No. 56(1981)-46474, to directly connect a rear frame member (rear side member) joined to the lower face of the rear floor panel of the body floor so as to form a closed cross-section structure extending in the longitudinal direction of the body with a front frame member (front side member) joined to the lower face of the front floor panel of the body floor thereby to form a closed cross-section structure extending in the longitudinal direction of the body. This automobile body structure is also provided with a cross member for improving the rigidity of the body in the crosswise direction thereof.
However, in the proposed automobile body structure, the closed cross-section structure formed by the floor panel and the rear frame member or the front frame member on either side of the vehicle body is simply positioned approximately in parallel with the side sill. Accordingly, the body structure cannot exhibit sufficient strength against a large torsional force. Further, since external loads such as impact loads exerted from the bumper are borne mainly by the closed cross-section structure formed by the rear frame member and the front frame member on either side of the body, the strength of the body structure against external loads is not sufficient.